#define _CRT_SECURE_NO_WARNINGS 1



#include<stdio.h>
#include<math.h>


int main()
{
	int a = 0, b = 0;
	scanf("%d %d", &a, &b);
	if (abs(a) <= 1 && abs(b) <= 1)
		printf("yes\n");
	else
		printf("no\n");

	return 0;
}